Large-sized commercial signboards with letters and illustrations have been placed for example on top of buildings or beside railroad tracks. These large-sized signboards are placed with an illumination apparatus for illuminating the display surface of the signboard during the night according to the size of the signboard.
Such an illumination apparatus includes a plurality of light emitting devices for illuminating the display surface of a signboard (member to be irradiated). The plurality of light emitting devices illuminate the display surface of the signboard from obliquely above or below (see, e.g., PTLS 1 and 2).
An illumination apparatus disclosed in PTL 1 includes a member to be irradiated and a plurality of lighting apparatuses (light emitting devices) for illuminating the member to be irradiated. The lighting apparatus are disposed at the bottom of the member to be irradiated such that the optical axis of emitted light from the lighting apparatuses is at an angle relative to the member to be irradiated.
An illumination apparatus disclosed in PTL 2 includes a member to be irradiated and an LED module for illuminating the member to be irradiated. The LED module (light emitting device) includes an LED (light emitting element) and a collimator lens (light flux controlling member) disposed over the LED. The collimator lens includes an incidence surface on which light emitted from the LED is incident, a reflection surface for reflecting the light incident on the incidence surface, and an emission surface for emitting the light reflected by the reflection surface toward the outside. The emission surface is formed such that the cross-section thereof is sawtooth-like so that light incident on the incidence surface propagates obliquely upward. The LED module is disposed such that the optical axis of emitted light therefrom is at angle relative to the member to be irradiated.